In a way, I think it's even worse than that. I've used Alexa since the Echo was a relatively new product. Back then, I experimented with new phrases and commands often, but was frequently greeted with wrong answers or "Sorry, I don't know how to help with that." Over time, I stopped trying those commands. Skip forward to today--the backend has been improving for years, and many of those commands now work, but it's too late. Their users have already been taught that they don't, so folks stop trying to use those features. Not only can you not discover new commands easily, you might mentally blacklist useful commands permanently.
Perhaps more frustratingly, the "What's New" emails they send out don't help with this. They never say "Hey, we know you tried to ask your Echo to report its volume level before and it didn't work, but it does now." They always say "Ask Alexa to tell you an Arbor Day joke!" -_-